Year	Percent
1991	46.876
1992	47.285
1993	47.482
1994	47.25
1995	47.094
1996	49.771
1997	49.668
1998	50.242
1999	50.466
2000	50.16
2001	50.147
2002	49.947
2003	49.684
2004	49.122
2005	48.751
2006	48.414
2007	47.844
2008	47.458
2009	46.272
2010	45.015
2011	43.874
2012	41.57
2013	40.402
2014	40.872
2015	36.969
2016	36.507
2017	36.295
2018	36.224
2019	36.159
2020	36.096
2021	36.034
2022	35.974